Review Sony SLT alpha 77 (So APS-C)

Ivo Freriks, 26 February 2012

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The Sony A77 replaces the Sony A700 and is the last descendant of the Sony Translucent Mirror cameras (SLT) series. These are SLRs with a fixed mirror, instead of a regular mirror which opens and closes taking a shot. The SLT makes it possible to take series of shots at higher speeds than what is physically possible for an SLR. The target group of the Sony A77 consists of advanced amateurs or professional photographers. Due to the choice of a semi-transparent mirror, combined with the choice of 24 megapixels on an APS-C sensor, Sony has not made it easy for itself.

For a good signal to noise ratio and high dynamic range, you need as much light per pixel as possible. And the choice for an SLT with a 24 megapixel APS-C sensor goes against the grain a bit. To what extent has Sony managed to maintain a high image quality?

The design of the camera body of the Sony A77 is decent, with a large amount of buttons on the body, giving you relatively little need to resort to the menu settings. The camera fits comfortably in your hand. To further enhance the user convenience, custom functions can be assigned to the AEL, AF/MF and ISO button.

Only adjusting the autofocus mode is less intuitive. Seen from the top, the button is left of the lens, ensuring you need to take the camera away from your face to switch this knob.

Sony A77 vs. Sony A65 or NEX-7

All three of these Sony cameras use the same 24 megapixel sensor and the same electronic viewfinder

The Sony A77 is larger than the Sony A65, but also better protected against water and dust

The Sony A77 has several features that you really only find on professional camera bodies, such as AF fine tuning, a top panel LCD, a joystick controller, built-in GPS (Sony A77V) and a magnesium body

Both the flash sync (1/250 sec) and the fastest shutter speed of the A77 (1/8000 sec) are faster than those of the A65

The LCD screen of the Sony A77 can move in 3 directions ("hinge/tilt/swivel"). The screen of the A65 can only do so in 2 directions (tilt/swivel).

Sony A77 versus Canon 7D / Canon 5D MK2, Nikon D5100

The Sony A77 has an electronic viewfinder and a fixed mirror. The other, traditional SLR cameras have an optical viewfinder and a flapping mirror

The Sony A77 offers a "peaking" function, where if you focus manually, what is in focus is indicated in the viewfinder.

The Sony A77 offers the latest features such as Face Detection, GPS and the most options for in-camera correction of vignetting, chromatic aberration and distortion. The Sony A77 also offers a HDR auto mode where 3 pictures can be combined into a HDR shot in the camera, and a level in the viewfinder.

Thanks to the semitransparent mirror, you can take up to 12 shots per second with the Sony A77

Viewfinder, screen and menu

The construction of the Sony A 77 is well made and the camera fits comfortably in your hand. Very nice about the control of the Sony A77 are the turning wheels at the front and back of the camera, allowing you to adjust the shutter speed and aperture separately without having to take the camera away from your face. With this, Sony provides the same functionality as the professional cameras of other brands.

The OLED 2.4M dots / 1024 x 768 viewfinder is really nice. You hardly notice that you are looking at an optical viewfinder, but at a little screen in the camera. The viewfinder accuracy of the bright electronic viewfinder is 100% according to Sony. It is pleasant, especially in sunny weather, to use this viewfinder. The viewfinder turns itself on when you bring the camera to your eye, or hangs in front of your belly.

The screen on the back of the camera can be tilted or rotated in 3 directions. The menu of the Sony A77 is very clear despite a large amount of features. Besides the regular menu, there is also a quick menu with settings that you access through a button on the back of the camera. It is nice that the two menus complement each other and do not partly provide the same functionality as you sometimes encounter with other camera brands. The Sony offers the possibility to correct all the in-camera jpg files for vignetting, chromatic aberration and distortion. That is a good development, because this can save a lot of time on finishing for critical photographers. But not all Sony lenses currently benefit from this feature.

The Peaking function at manually focusing highlight in white, red or yellow which is in focus. It is based on an open aperture. The effect of stopping down is not shown.

We have tested the Sony A77 in combination with Sony 16-50 mm. But this camera is also used to test for example the Sony 70-400 mm and the legendary Sony 24-70 mm. Besides the practical test of the Sony A77, we have also subjected the Sony A77 to a series of Imatest measurements. The Imatest measurement results are shown in the Sony A77 test report. For the test method and explanation of terms, see the FAQ.

Resolution / sharpness

The Sony A77 delivers, in combination with the Sony 16-50 mm, jpg files with a resolution up to 2500 LW/PH. The resolution remains fairly constant over the ISO range of 50 ISO to 12,800 ISO. At 25,600, the resolution drops to about 1000 LW/PH, probably due to the noise reduction that firmly starts at the highest ISO sensitivity.

With a standard editing of the RAW files in Lightroom, no greater sharpness impression is obtained. The RAW files gave an average resolution of nearly 2000 LW/PH across the ISO range. With cameras from Nikon and Canon, a RAW file gives a higher sharpness impression; at Sony, the resolution of a RAW file that we edited in the same way is just slightly lower than of in-camera jpg files. An explanation for this can be found in the Sony A77 test report.

Click on the left image to see an impression of the resolution of an ISO 100 jpg file at 100%.

Move your mouse over the right image to see a comparison of a jpg file (2500 LW/PH) with a standard modified RAW file (2000 LW/PH).

Sony DT 16-80 mm f/3.5 – 4.5 VR @ 22 mm, 100 ISO, f/8, 1/800 s

Dynamic range

The with Imatest measured total dynamic range of the Sony A77 sensor is dependent on the ISO setting, between the 10 and 13 stops, both for a raw file and for a JPG file. Here, the Sony A77 differs little from other cameras like the Nikon D5100 or the Canon 60D.

But more important than the total dynamic range is the usable dynamic range. The signal/noise ratio helps determine what remains from the dynamic range for a displayable image. At 50 and 100 ISO, the usable dynamic range of the Sony A77 is very high due to the low noise, see below, with 8 stops for a RAW file and even 10 stops for a jpg file.

Above ISO 100 the doubling of the ISO value allows a decrease of one and a half stops of the usable dynamic range. At ISO 3200, the usable dynamic range of a RAW file without noise reduction is reduced to 0 stops. By applying a large amount of in-camera noise reduction, Sony gets to realize a large useful dynamic range of RAW files, as you can see in the practice shooting on the left. Even in the shadows, the noise is low.

Noise

The signal to noise ratio of the Sony A77 is an exciting story. Because 24 megapixels are crammed on an APS-C sensor, you expect more noise than with cameras with a full-frame sensor or other cameras with an APS-C sensor with fewer pixels. Here, the Sony A77 surprises positively at low ISO settings. At 50 ISO, the noise of the Sony A77RAW file is as low as the noise of a Nikon D700 or Canon 5D MK2 RAW file at ISO 50 or 100. The Sony A77 scores better here than the Nikon D5100 or the Canon 60D. For jpg files at low ISO settings, more or less the same goes: the noise of jpg files of the Nikon D700 @ ISO 100 or the Sony A 77 @ 50 ISO is lower than the noise of jpg files of the Canon 5D MK2, Canon 60D or the Nikon D5100.

At higher ISO settings, the story is something else. Above the 1600 ISO, you see the noise of RAW files greatly increase and the noise reduction of jpg files proceeds more aggressively. Here you see an image cropping of an ISO 3200 jpg practice shot, made in the dark.

Move your mouse over this ISO 3200 jpg shot to view a 100% image crop to assess the noise and sharpness.

With HDR images, dark areas are lit in the digital darkroom. Here, noise in dark areas becomes much more visibly or even more disturbingly present. This makes HDR recordings, although extreme, good illustrations of the quality of a camera in terms of signal to noise ratio.

Here you see a 100% image cropping of an ISO 200 HDR shot, including standard noise reduction in Lightroom. At ISO 3200, the noise is so strong that the image is no longer usable for HDR. Here, you would have to apply so much noise reduction, you lose a lot of resolution.

Hold the mouse over the image to view an enlargement of 100% of an HDR shot at 200 ISO with noise reduction and 3200 ISO without noise reduction.

Color reproduction

In terms of color reproduction in daylight, all tested cameras are pretty similar so far. The Imatest measurement results in the Sony A77 test report confirm the quality of practice shots.

The Sony A77 delivers saturated images with good color reproduction in daylight. The color deviation (delta E 94) is small for both an in Lightroom converted RAW file and a jpg file (neutral) directly from the camera. The automatic white balance of the Sony A77 does its job well.

Images made in the shade are sometimes a little too cool or blue, as we noticed during the field test. The Sony A77 is better in terms of color reproduction and white balance in artificial light than previously tested cameras like the Canon 5D MK2, Nikon D700 or Canon 60D. Shots made in artificial light do have a less accurate color reproduction than images taken in daylight. But both can be easily improved with a small manual adjustment of the white balance.

Built-in flash

An external flash can be connected to the Sony A77. However, the Sony A77 also has a little built-in flash, which is suitable for lenses having a focal length up to 24 mm. In this test, we have not further investigated the flash. If you buy such a beautiful camera, you should also buy a good flash, I think.

Autofocus

The autofocus on the Sony A77 is fast and accurate. With sufficient light, the camera is confident and quick, suited for sports photography or other sports that require much of the AF speed for sure. In many SLR camera's, the mirror reflects a part of the light to the AF sensor. If Sony applies the same principle, in low light or with subjects with little contrast, the autofocus on the Sony A77 could in theory start to hunt sooner than with a traditional SLR, because the AF module only has 30% of the light available to him, the rest of the light goes to the sensor. We've contacted Sony about this topic: According to the Sony spokesman SLT camera's are even performing better in low light for AF because the AF sensor has a little bit more wide angle and receives even more light than the traditional SLR's.

"Also a mirror of a regular SLR (with Live View) is a semi translucent mirror. Most of the light which passes the lens will be reflected to the penta prism to get the image in the Optical Viewfinder.At the same time some of the light will pass this mirror and will be reflected to the Auto Focus sensor situated in the bottom part of the camera. So also in a regular SLR, the amount of light which will reach the AF sensor is quite lower. In my opinion the SLT camera's are even performing better in low light for AF because the AF sensor has a little bit more wide angle and receives even more light than the traditional SLR's. And of course the unique benefits of Translucent technology like quick shooting, up to 12 fps / fast recording with moving pictures in screen and last but not least phase detection AF video recording."

I have the impression that the focal length or maximum aperture and the design date of the lens have a much greater impact on whether or not hunting of the autofocus than the camera will occur. The older the design of a lens or longer the focal length, the more effort the Sony A77 has with focusing in the dark. With the Sony 16-50 mm 2.8, - a recent and bright lens with a finite focal length - focusing in the dark was easy. With the Sony 70 - 300 mm, focusing in the dark went well, but slower. With the Sony 70-400 mm, the Sony A77 sometimes started to hunt when focusing in the dark.

Autofocus tracking

The Sony A77 succeeds in bright light to take a series of sharp shots of a car traveling at 50 km/h right at the camera. This is a very good performance, which makes this camera also a good choice for sports photographers. Until now, of the cameras we tested, the Nikon D700 was the only one capable of this. At the point of autofocus tracking, the Sony A77 leaves for example the Nikon V1, Panasonic G3, Canon 60D or the Canon 5D MK2 far behind.

Click the right picture for some 100% images crops of the focus tracking series of the Sony A77.

Pros

Cons

Large and heavy compared to the Sony NEX-7, which is expected to provide at least the same image quality

Dynamic range and signal to noise ratio at high ISO settings

The Sony A77 is a very good camera with great ease of use. The ease of use is not only because of all the possible functions on the camera, but also because of the accessibility of the menus and pleasant ergonomics. In terms of image quality, this is the best camera with an APS-C sensor that we have tested so far. Sony has managed to make a sensor with low noise and a high dynamic range at the low ISO settings. The sharpness of jpg files is even higher than of the Canon 5D Mk2, a camera with a full-frame sensor.

With Camera Review Stuff I hope to make a modest contribution to the pleasure that you get from photography. By testing cameras and lenses in the same way, evluating the results and weighing up the pros and cons, I hope to help you find the right camera or lens.

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Comments (3)

"The autofocus on the Sony A77 should in theory be able to hunt sooner than with a traditional SLR, because the AF module only has 30% of the light available to him"<br /><br />Regula SLR has to provide the light to three thingss:<br /><br...

"The autofocus on the Sony A77 should in theory be able to hunt sooner than with a traditional SLR, because the AF module only has 30% of the light available to him"<br /><br />Regula SLR has to provide the light to three thingss:<br /><br />(1)AF sensor<br />(2) Optical viewfinder<br />(3) metering sensor<br /><br />So your "theory" isn't right

Hi Riz, <br /><br />Thanks for your feedback. We strive to improve our website constantly and your comment is very welcome!<br /><br />The assumption I made, without much further investigation I must admit, was that the Sony A77 AF-module has a...

Hi Riz, <br /><br />Thanks for your feedback. We strive to improve our website constantly and your comment is very welcome!<br /><br />The assumption I made, without much further investigation I must admit, was that the Sony A77 AF-module has a similar design as older Sony SLR cameras without a semitranslucent mirror. <br />Which means: the A77's AF sensor sits at the same position and is equally large as the AF sensor in a Sony SLR without a Semitranslucent mirror. If the only difference between the A77 AF system and a traditional SLR is the reflection efficiency of the mirror, there should be a difference. I will take some time to investigate whether I made a wrong assumption and I will let you know my findings.

Dear Ivo,<br />I agree with everything in this review... except the final score which you give to this camera. I do not understand how after praising it in almost all areas (except the noise at high ISO), and stating it as superior or equal to...

Dear Ivo,<br />I agree with everything in this review... except the final score which you give to this camera. I do not understand how after praising it in almost all areas (except the noise at high ISO), and stating it as superior or equal to many cameras, it ends up getting only a 6.8... the lowest score of all the cameras you reviewed. Don't you think it deserves at least a bit more?<br />Best regards,<br />Nassim Bovet<br /><br />P.S. I hope you don't mind my (constructive, I think) criticism... it shows I read your reviews with attention!